Chevrolet 1993 S-10 Pickup Owner's Manual page 274

Service & Appearance Care
Radiator Pressure Cap
KO721
When you replace your radiator pressure cap, an AC@ cap is recommended.
See "Service Replacement Part and Filter Recommendations" in the Index.
Thermostat
Engine coolant temperature is controlled by a thermostat in the engine coolant
system. The thermostat stops the flow
of
coolant through the radiator until the
coolant reaches a preset. temperature.
When you replace your thermostat, an AC@ thermostat is recommended.
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